1. Field of the Invention
This invention relates to electronic communication linkage security systems, and more particularly to an improved electronic computer linkage interface control security system and method for providing secure communications access between digital data devices.
2. Related Art
As computer usage increases, and particularly as the scope of computer communication network system usage increases, a greater number of computer users potentially have access to any one computer system. Hence, the need exists for increased security for such computer systems by limiting computer access to only authorized users. One manner of controlling such access is to permit only authorized terminals to be used in accessing a main computer. While a variety of computer access control systems have been proposed in the past, most such systems rely solely on presentation of a computer terminal password or identification number to a main computer system for comparison with stored data records so as to verify the authorization of that terminal to access the computer. Such simple password or identification schemes are subject to failure if a determined effort is made to evade or corrupt the security system. For example, a determined unauthorized user may actually be able to intercept an authorized terminal's password or identification number during a communication session between an authorized user on an authorized terminal and a main computer. Thereafter, the unauthorized user may be able to surreptitiously obtain access to the main computer using the intercepted password or identification number to emulate an authorized terminal.
Therefore, it is an object of this invention to provide a low cost digital data communications linkage interface control system and method for more reliably controlling access from a computer terminal to a main computer over a communications linkage and to minimize or eliminate the possibility of using an intercepted copy of the terminal's password or identification number. The present invention achieves this object by means of a simple electronic circuit combined with a method implemented by means of a computer program for regulating such access to authorized terminals only.